jclb unit 3

z/OS MVS JCL Intermediate

© Copyright IBM Corp., 2000, 2004. All rights reserved.


© Copyright IBM Corp., 2000, 2004. All rights reserved. of 58

UNIT Modifying EXEC Parameters

Analyzing Procedures

Changing EXEC Parameters

Override Statements

Nullification Statements

Addition Statements

Sequencing Multiple Changes

Topics:



Before using a procedure it is essential to ensure that it meets all the processing requirements. This mightinvolve some minor alterations to the procedure to ensure that it has all the requirements to execute the job.

This unit describes how to alter EXEC statement parameters at the time of job submission. The informationcontained in this unit can be applied to both in-stream and cataloged procedures.

Unit Introduction

Unit: Modifying EXEC Parameters

Introduction



At the end of this unit, you will be able to:

• Specify what factors determine if a procedure meets the requirements of a job

• Invoke a procedure, making temporary alterations to it if necessary

• Add, override or nullify parameters on procedure step EXEC statements

• Correctly sequence multiple changes to EXEC statement parameters

Unit Objectives


Introduction





Changing EXEC Parameters

Override Statements


Addition Statements


Topics:



At the end of this topic, you will be able to:

• Analyze a procedure listing

Topic Objectives

Unit: Modifying EXEC Parameters Topic: Analyzing Procedures

Introduction



A procedure listing is obtained and examined toensure that it meets the following two criteria:

• The procedure invokes the proper programs in the desired sequence

• Most of the DD statements are usable without major alteration

Identifying Analysis Criteria


Concepts



Consider a case in which a company buys goodswholesale from several manufacturers andmarkets them retail to other customers.

Each week the customer order departmentcreates a transaction file that contains newcustomer orders for the week.

A list of orders to be filled is sent to thewarehouse and an invoice is sent to eachcustomer. The order list and associated invoicesare printed once a week.

Identifying Analysis Criteria - An Example


Continued…Concepts



A program named PROG1 checks the weeklyinput transactions against entries in a mastercustomer data set. Valid transactions are writtento a new data set used as input for anotherprogram named PROG2.

PROG1 refers to the following data sets:

DD1: Refers to the input transactions

DD2: Refers to the master customer data set

DD3: Refers to the transaction exception report

DD4: Refers to the set of valid transactions that are passed to PROG2

Identifying Analysis Criteria - An Example (cont’d)





PROG2 reads the valid transactions passed fromPROG1 and creates an order list/invoice for eachcustomer.

PROG2 refers to the following data sets:

DD5: Refers to the set of valid transactions passed from PROG1

DD6: Refers to the order list/invoice for each customer






Shown on the right is the procedure namedTRANSACT that is used to accomplish this task.

A procedure listing is obtained to determine:

• If it uses the required programs in the required sequence

• If it uses appropriate data sets



//PSTEP1 EXEC PGM=PROG1,TIME=(1,30)//DD1 DD DSN=INTRAN,DISP=SHR//DD2 DD DSN=MASTER,DISP=SHR//DD3 DD SYSOUT=A//DD4 DD DSN=&&VALID,// UNIT=SYSDA,DISP=(NEW,PASS),// SPACE=(TRK,(1,1))//PSTEP2 EXEC PGM=PROG2,TIME=5//DD5 DD DSN=&&VALID,// DISP=(OLD,DELETE)//DD6 DD SYSOUT=A

Concepts



Based on the analysis of the JCL in the previous example, do you think this is an appropriate procedure for the task, as described?

A. No, because not all data sets are taken into consideration.

B. There is not enough information to decide.

C. Yes, because both criteria are met.

Are We on Track?


Review



The listing for the procedure TRANSACTindicates the following:

The procedure executes 2 programs: PROG1 and PROG2.

PROG1 uses the following data sets:

• A cataloged data set named INTRAN(DD1 DD statement)

• A cataloged data set named MASTER(DD2 DD statement)

• SYSOUT class A output (DD3 DDstatement)

• A temporary data set named &&VALIDthat is passed to PROG2 (DD4 DD statement)

Analysis Explanation


Continued…


Concepts



PROG2 uses the following data sets:

• A temporary data set named &&VALID,which is passed from PROG1 (DD5 DDstatement)

• SYSOUT class A output (DD6 DDstatement)

In addition, a TIME parameter is included on thePSTEP1 and PSTEP2 EXEC statements torestrict the amount of time the programs arepermitted to use the central processor.

Analysis Explanation (cont’d)


Continued…


Concepts



The TRANSACT procedure listing is obtained and evaluated to ensure that the procedure executesall the required programs in the proper sequenceand the appropriate data sets are used to accomplish the application.

Analysis Explanation (cont’d)

Concepts

Topic: Analyzing ProceduresUnit: Modifying EXEC Parameters



Code a statement to invoke transact.

//JSTEP EXEC __________

Are We on Track?


Review



A procedure must meet which of the following criteria?

A. Most of the DD statements are usable as they are or might need some minor alteration.

B. The programs in the procedure are located in the same library.

C. It invokes the proper programs in the correct sequence.

D. The DD statements point to a single storage volume.

Are We on Track?


Review



Cataloged data set – A non-temporary data set for which the system has recorded the unit and volume on which the data set resides.

SYSOUT – A keyword that defines a print data set. It instructs the system to queue the output on a direct-access volume.

Temporary data set – A data set which stores data needed only for the duration of the job.

Glossary


Glossary



Now that you have completed this topic, you should be able to:

• Analyze a procedure listing

Topic Summary


Summary





Changing EXEC parameters

Override Statements


Addition Statements


Topics:




• Identify the EXEC statement parameters that can be changed

• Explain how to implement changes to EXEC statement parameters

Topic Objectives

Unit: Modifying EXEC Parameters Topic: Changing EXEC Parameters

Introduction



A procedure listing helps a programmer to analyzethe procedure for its usability. In some cases aprocedure might satisfy all the basic requirementsfor usability, but might need some minoralterations.

This can be done by changing the EXEC and DD parameters when the procedure is invoked.

However, these alterations are applicable only forone invocation. They do not permanently modifythe procedure definition.

Coding Changes





Changes can be made to procedure EXECstatement parameters such as TIME, ACCT, andPARM.

The programmer can change these parametersin the following ways:

• Override the parameters on theprocedure EXEC statement

• Nullify parameters on the procedureEXEC statement

• Add parameters to the procedure EXECstatement

Coding Changes (cont’d)


//STEP1 EXEC procedure name,parameter

//DD1 DD parameter

//DD2 DD parameter Override

Nullify

Add

New DD Statement

Concepts



General syntax for changes to EXEC statement parameters is as follows:

//JSTEP EXEC procedurename,// parameter.procstepname=value

Implementing coding changes to EXEC statements involves the following steps:

• Give the name of the EXEC statement parameter to be overridden, nullified or added, followed by a period.

• Give the name of the procedure step, followed by an equal sign.

• Give the new value for the parameter if overriding or adding a value. Do not code a value if the parameter is to be nullified.

Implementing Coding Changes


Changes are specified in the EXEC statement that invokes the procedure.

Concepts


© Copyright IBM Corp., 2000, 2004. All rights reserved. of 58Review

Changing parameters at the time you invoke a procedure has what effect?

A. Changes apply to the number of invocations you specify in the JCL.

B. Changes apply to all procedures containing the edited parameters.

C. Changes apply once only to the current invocation.

D. Changes apply to all future invocations of the procedure.

Are We on Track?


Review



Which of the following changes can you make at the time you execute a procedure?

A. Temporarily add operands such as ACCT to procedure EXEC statements

B. Alter the library copy of the JCL contained in cataloged procedure

C. Override the PGM parameter on procedure EXEC

Are We on Track?


Review


© Copyright IBM Corp., 2000, 2004. All rights reserved. of 58Introduction


• Identify the EXEC statement parameters that can be changed

• Explain how to implement changes to EXEC statement parameters

Topic Summary


Summary






Override Statements


Addition Statements


Topics:




• Explain how to override parameters in an EXEC statement that invokes a procedure

Topic Objectives

Unit: Modifying EXEC Parameters Topic: Override Statements

Introduction



An override statement is used to change anexisting parameter value.

Consider the TRANSACT procedure discussedin Unit 3, Topic 1 – Analyzing procedures. The procedure definition is shown on the right.

Note that the time that PROG1 can run is 1minute 30 seconds.

Assume that for a particular week, the transaction file to be processed is too large andthe time that PROG1 can run needs to beincreased to 3 minutes.

Overriding Statement Parameters



//PSTEP1 EXEC PGM=PROG1,TIME=(1,30)//DD1 DD DSN=INTRAN,DISP=SHR//DD2 DD DSN=MASTER,DISP=SHR//DD3 DD SYSOUT=A//DD4 DD DSN=&&VALID,// DISP=(NEW,PASS),// UNIT=SYSDA,// SPACE=(TRK,(1,1))//PSTEP2 EXEC PGM=PROG2,TIME=5//DD5 DD DSN=&&VALID,// DISP=(OLD,DELETE)//DD6 DD SYSOUT=A



To override the original time parameter, theTRANSACT can be invoked with the followingEXEC statement:

//JSTEP EXEC TRANSACT,TIME.PSTEP1=3

Shown on the right is the resulting JCL.

Note the new parameter in the resulting JCL.However, this override is only temporary. Theprocedure definition does not change. The nexttime the procedure is invoked, it will revert to theoriginal definition.

Overriding Statement Parameters (cont’d)


//PSTEP1 EXEC PGM=PROG1,TIME=3//DD1 DD DSN=INTRAN,DISP=SHR//DD2 DD DSN=MASTER,DISP=SHR//DD3 DD SYSOUT=A//DD4 DD DSN=&&VALID,// DISP=(NEW,PASS),// UNIT=SYSDA,// SPACE=(TRK,(1,1))//PSTEP2 EXEC PGM=PROG2,TIME=5//DD5 DD DSN=&&VALID,// DISP=(OLD,DELETE)//DD6 DD SYSOUT=A

Concepts


© Copyright IBM Corp., 2000, 2004. All rights reserved. of 58Review

Following is a portion of the JCL for a procedure named MYPROC.

//PSTEP1 EXEC PGM=PROGA,TIME=(3,30)//DD1 DD DSN=A,DISP=SHR//DD2 DD ...//PSTEP2 EXEC PGM=PGMB,TIME=5//DD3 DD ...

Code a statement to invoke the procedure named MYPROC. Assume you want to restrict the amount of time PROGA is permitted to use the CPU to 2 minutes.

//JSTEP EXEC ______________

Are We on Track?


Review


© Copyright IBM Corp., 2000, 2004. All rights reserved. of 58Introduction


• Explain how to override parameters in an EXEC statement that invokes a procedure

Topic Summary


Summary






Override Statements


Addition Statements


Topics:




• Explain how to nullify parameters in an EXEC statement that invokes a procedure

Topic Objectives

Unit: Modifying EXEC Parameters Topic: Nullification Statements

Introduction



A procedure can be modified by nullifying an EXECstatement parameter.

Most installations have values that are assigned toEXEC statement parameters automatically. Forexample, a default value may be assigned for theTIME parameter.

The default values may be overridden when theprocedure is defined. To return to the installation’sdefault value, the programmer can code astatement that nullifies the parameter.

Nullifying EXEC Statement Parameters


To nullify a parameter means to change it back to the installation-defined default. Continued…

Concepts



The format for nullifying an EXEC statement parameter is:

//JSTEP EXEC procedurename,// parameter.procstepname=

Note that in the format, the programmer specifies the parameter and the procedure step in which it appears.Also note that no value is assigned to the parameter in the nullifying EXEC statement.

Nullifying EXEC Statement Parameters (cont’d)


Concepts



Consider the TRANSACT procedure discussedin Unit 3, Topic 1 – Analyzing procedures.

The procedure definition for PROG1 (in theprocedure step PSTEP1) has specified a CPUtime of 1 minute 30 seconds for processing atransaction file. This processing time may not beadequate for a larger file.

If the default time is adequate, the programmermight want to execute the procedure taking thesystem default time for PROG1.

Nullifying EXEC Statement Parameters – An Example


Continued…


Concepts



To do this, the programmer needs to nullify theTIME specified in the procedure definition on thePSTEP1 EXEC statement.

The following EXEC statement which invokesTRANSACT would nullify the time parameter:

//JSTEP1 EXEC TRANSACT,TIME.PSTEP1=

The resulting JCL is shown on the right.

Nullifying EXEC Statement Parameters – An Example (cont’d)


//PSTEP1 EXEC PGM=PROG1//DD1 DD DSN=INTRAN,DISP=SHR//DD2 DD DSN=MASTER,DISP=SHR//DD3 DD SYSOUT=A//DD4 DD DSN=&&VALID,// DISP=(NEW,PASS),// UNIT=SYSDA,// SPACE=(TRK,(1,1))//PSTEP2 EXEC PGM=PROG2,TIME=5//DD5 DD DSN=&&VALID,// DISP=(OLD,DELETE)//DD6 DD SYSOUT=A

Concepts




//PSTEP1 EXEC PGM=PGMA//DD1 DD ...//PSTEP2 EXEC PGM=PGMB,TIME=5 //DD2 DD ...

Assume that for this use of the procedure, you want to return to the installation-defined CPU time limit for PROGB. Code the statement to invoke MYPROC.

//JSTEP EXEC __________

Are We on Track?


Review




• Explain how to nullify parameters in an EXEC statement that invokes a procedure

Topic Summary


Summary






Override Statements


Addition Statements


Topics:




• Explain how to add parameters in an EXEC statement that invokes a procedure

• Specify the steps involved in multiple addition ofparameters

Topic Objectives

Unit: Modifying EXEC Parameters Topic: Addition Statements

Introduction



Addition statements are used to add parameters to a procedure. The programmer can code additions on the

EXEC statement that invokes the procedure.

Consider the TRANSACT procedure discussed in Unit 3, Topic 1 – Analyzing procedures. Assume that aprogrammer wants to supply the current date for PROG1.

This parameter can be coded in the following way while invoking the procedure:

//JSTEP EXEC procedurename,// parameter.procstepname=value

//JSTEP EXEC TRANSACT,// PARM.PSTEP1=’01/29/99’

Adding Parameters to a Procedure


Addition




Parameters can be added to one or more procedure steps. In the TRANSACT procedure, the current datecan be supplied to PROG1 and PROG2 by means of the PARM parameter.

The code would be as follows:

//JSTEP EXEC TRANSACT,// PARM.PSTEP1=’01/29/99’,// PARM.PSTEP2=’01/29/99’

Note the following points when sequencing multiple EXEC statement additions:

• The additions are in procedure step sequence.

• A comma separates the name of the procedure from the first parameter addition, and the parameter additions from each other.

Adding Parameters to a Procedure (cont’d)





The TRANSACT procedure definition is shown onthe right.




Concepts

Continued…



The following EXEC statement supplies thecurrent date for PROG1 and PROG2:

//JSTEP EXEC TRANSACT,// PARM.PSTEP1=’01/29/91’,//

PARM.PSTEP2=’01/29/91’

The resulting JCL is shown on the right.



//PSTEP1 EXEC PGM=PROG1,TIME=(1,30)// PARM=’01/29/91’//DD1 DD DSN=INTRAN,DISP=SHR//DD2 DD DSN=MASTER,DISP=SHR//DD3 DD SYSOUT=A//DD4 DD DSN=&&VALID,// DISP=(NEW,PASS),// UNIT=SYSDA,// SPACE=(TRK,(1,1))//PSTEP2 EXEC PGM=PROG2,TIME=5// PARM=’01/29/91’//DD5 DD DSN=&&VALID,// DISP=(OLD,DELETE)//DD6 DD SYSOUT=A

Concepts




//PSTEP1 EXEC PGM=PGMA,TIME=(1,30)//DD1 DD ...//PSTEP2 EXEC PGMB,TIME=5

Assume that for this invocation of MYPROC, you wish to add the date 01/11/99 to PROGA and PROGB. (You do so through the PARM parameter.)

Code the statement to invoke MYPROC.

Are We on Track?


Review



Match the change types below with their descriptions.

1. Override A. Append existing code with new parameters

2. Nullify B. Change a parameter back to its default value

3. Addition C. Change an existing value

Are We on Track?


Review




• Explain how to add parameters in an EXEC statement that invokes a procedure

• Specify the steps involved in multiple addition ofparameters

Topic Summary


Summary






Override Statements


Addition Statements


Topics:




• Explain how to combine changes to EXEC statement parameters

• Specify the rules involved in sequencing multiple changes

Topic Objectives

Unit: Modifying EXEC Parameters Topic: Sequencing Multiple Changes

Introduction



It is possible to use EXEC statement overrides, nullifications, and additions for one or more procedure steps

at the same time. This can be done by combining the changes on the EXEC statement that invokes theprocedure.

For example, the programmer can change the time restrictions and can also supply the current date for aparticular PSTEP.

Combining Changes


Concepts



The following rules must be followed while sequencing multiple changes:

• Specify alterations in procedure step sequence. The alterations for one step must be specifiedbefore the alterations for a subsequent step.

• Within any one step, alterations can be specified in any sequence.

• Alterations should be separated from each other by a comma.



Concepts



Consider the TRANSACT procedure discussedin Unit 3, Topic 1 – Analyzing procedures.The following alterations are to be made to theEXEC statement operands in the procedure:

• Increase the time restriction for PSTEP1 to 3 minutes

• Revert to the installation-defined TIME default for PSTEP2

• Add a PARM parameter value of 01/29/99 for the EXEC statements in PSTEP1 and PSTEP2

The JCL statements on the right show how tocombine these alterations on the EXEC statementthat invokes the procedure.

Sequencing Multiple Changes – An Example


//JSTEP EXEC TRANSACT,TIME.PSTEP1=3,// PARM.PSTEP1=’01/29/99’,// TIME.PSTEP2=,// PARM.PSTEP2=’01/29/99’

Concepts



For the invocation of MYPROC, assume you want to make the following changes:

a. Revert to the installation-defined CPU time limit for PROGB.b. Restrict the amount of time PROGA can use the CPU to 2 minutes.c. Add a PARM value of ‘5/10/99’ to PROGA.

Put the following items in the correct sequence, following the sequencing rules for multiple changes to produce EXEC statement parameters.

A. // PARM.PSTEP=‘5/10/99’

B. // TIME.PSTEP1=2

C. //JSTEP EXEC MYPROC,

D. // TIME.PSTEP2=

Are We on Track?


Review




• Explain how to combine changes to EXEC statement parameters

• Specify the rules involved in sequencing multiple changes

Topic Summary


Summary



Now that you have completed this unit, you should be able to:

• Specify what factors determine if a procedure meets the requirements of a job

• Invoke a procedure, making temporary alterations to it if necessary

• Add, override or nullify parameters on procedure step EXEC statements

• Correctly sequence multiple changes to EXEC statement parameters

Unit Summary


Summary

jclb unit 3

Documents